.book-box{
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    position: relative;
}
.book-calss-top{
    width: 100%;
    position: fixed;
    top: 0;
   
   
}
.book-calss-bottom{
   width: 100%;
   flex: 1;
   overflow-y: scroll;

}